Friction coupling
Abstract
A friction coupling comprising first and second coupling surfaces. A friction surface is provided on the first coupling surface and a counterface is provided on the second coupling surface. The friction coupling further comprises preload elements, such as bolts, for applying a predefined pressure on the first and second coupling surfaces. The friction surface of the coupling comprises abrasive particles that constitute hard asperities which protrude from a substrate of the friction surface with a height h. The abrasive particles are provided on the substrate in a predefined asperity density η. The predefined asperity density η is greater than a minimum threshold for the asperity density η min and is less than 2.5*η min . The minimum threshold is defined by the following relationship: η min = π 4 P H μ abr 2 h _ 2 + σ 2 where η asperities per unit (surface area) (m −2 ); P pressure (Pa); μ abr coefficient of friction; H hardness (counterface) (Pa) h height (asperities) (m); σ standard deviation (asperity heights) (m).
Claims
exact text as granted — not AI-modified1 . A friction coupling comprising:
a first coupling surface and a second coupling surface, wherein a friction surface is provided on the first coupling surface and a counterface is provided on the second coupling surface; and preloading means elements adapted to apply a predefined pressure on the first coupling surface and the second coupling surface, wherein the friction surface is provided with abrasive particles that constitute hard asperities which protrude from a substrate of the friction surface with a height h, wherein the abrasive particles are provided on the friction surface in an asperity density η, which density is greater than a minimum threshold for the asperity density η min and which density η is less than 2.5*η min , whereby the minimum threshold is defined by the following relationship:
η
min
=
π
4
P
H
μ
abr
2
h
_
2
+
σ
2
where
η represents number of asperities per unit surface area of the friction surface (m −2 );
P represents the predefined pressure (Pa);
μ abr represents a coefficient of abrasive friction between the friction surface and the counterface (dimensionless);
H represents a hardness of the counterface (Pa)
h is a mean height of the asperities (m);
σ is the standard deviation of asperity heights (m).
2 . The friction coupling according to claim 1 , wherein the asperity density η in which the abrasive particles are provided is less than 2.0*η min .
3 . Friction The friction coupling according to claim 1 ,
wherein the asperity density i in which the abrasive particles are provided is less than 1.5*η min .
4 . The friction coupling according to claim 1 ,
wherein the friction surface is formed by a coating comprising a metal bond layer in which the abrasive particles are embedded.
5 . The friction coupling according to claim 4 , wherein the metal bond later comprises Nickel,
wherein the abrasive particles comprise one of diamond particles or synthetic diamond particles.
6 . The friction coupling according to claim 1 , wherein the friction surface is provided on at least one face of an annular friction disk that is mounted to the first coupling surface.
7 . The friction coupling according to claim 6 ,
wherein the annular friction disk is formed from a plurality of segments, each segment having a friction surface.
8 . The friction coupling according to claim 1 ,
wherein the friction surface is provided directly on the first coupling surface.
9 . The friction coupling according to claim 1 ,
wherein the preload means elements are formed by one of a bolt connection, a screw connection or a rivet connection between the first coupling surface and the second coupling surface.
10 . A friction disk for use in a friction coupling, the friction coupling comprising:
the friction disk comprising: a friction surface of abrasive particles embedded in a metal bond layer, wherein the friction surface has an asperity density η of between 100 and 200 abrasive particles per square millimeter.
11 . A method of determining if a friction coupling comprising a friction surface and a counterface will be capable of delivering a desired level of torque transfer when subjected to a predefined operating pressure P, wherein the friction surface is provided with abrasive particles that form hard asperities which protrude from the friction surface with a height h, and wherein the counterface has a hardness H, the method comprising steps of:
a. determining an abrasive coefficient of friction μ abr between the friction surface and the counterface; b. determining the hardness H of the counterface; c. measuring the following parameters in at least a region of the friction surface:
(i) the number of asperities per unit surface area, corresponding to an asperity density η;
(ii) the mean height h of the asperities;
(iii) the standard deviation of asperity heights σ;
d. determining that the friction coupling is capable of delivering the desired level of torque transfer if η>η min whereby
η
min
=
π
4
P
H
μ
abr
2
h
_
2
+
σ
2
.
12 . The method of claim 11 , the step of determining that the friction coupling is capable of delivering the desired level of torque transfer if η>η min further comprising a step of determining that the friction coupling is capable of delivering the desired level of torque transfer in a condition where η>X*η min , whereby X is a safely factor.
13 . The method according to claim 12 , wherein X has a value of between 1.2 and 2.5.
14 . The method according to claim 10 , wherein the step of determining the hardness H of the counterface further comprising a step of measuring one of a Rockwell C hardness or an equivalent hardness of the counterface.
15 . The method according to claim 10 , the step of determining the hardness H of the counterface further comprising a step of calculating the hardness of the counterface according to the following formula:
H
=
2
3
Y
(
1
+
ln
π
E
μ
abr
6
(
1
-
v
2
)
Y
)
where
Y is the yield stress of the counterface (Pa)
E is the elastic modulus of the counterface (Pa) and
v is the Poisson ratio of the counterface.Join the waitlist — get patent alerts
Track US2016186817A1 — get alerts on status changes and closely related new filings.
We store only your email — no account needed. See our privacy policy.